ENGINE CONTROL SYSTEM
EC-549
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EC
MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system provides the best air-fuel mixture ratio for driveability and emission control.
The three way catalyst (manifold) can then better reduce CO, HC and NOx emissions. This system uses
heated oxygen sensor 1 in the exhaust manifold to monitor whether the engine operation is rich or lean. The
ECM adjusts the injection pulse width according to the sensor voltage signal. For more information about
heated oxygen sensor 1, refer to EC-666, "
DTC P0132 HO2S1" . This maintains the mixture ratio within the
range of stoichiometric (ideal air-fuel mixture).
This stage is referred to as the closed loop control condition.
Heated oxygen sensor 2 is located downstream of the three way catalyst (manifold). Even if the switching
characteristics of heated oxygen sensor 1 shift, the air-fuel ratio is controlled to stoichiometric by the signal
from heated oxygen sensor 2.
Open Loop Control
The open loop system condition refers to when the ECM detects any of the following conditions. Feedback
control stops in order to maintain stabilized fuel combustion.
Deceleration and acceleration
High-load, high-speed operation
Malfunction of heated oxygen sensor 1 or its circuit
Insufficient activation of heated oxygen sensor 1 at low engine coolant temperature
High engine coolant temperature
During warm-up
After shifting from N to D (A/T models)
When starting the engine
MIXTURE RATIO SELF-LEARNING CONTROL
The mixture ratio feedback control system monitors the mixture ratio signal transmitted from heated oxygen
sensor 1. This feedback signal is then sent to the ECM. The ECM controls the basic mixture ratio as close to
the theoretical mixture ratio as possible. However, the basic mixture ratio is not necessarily controlled as orig-
inally designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and characteristic
changes during operation (i.e., injector clogging) directly affect mixture ratio.
Accordingly, the difference between the basic and theoretical mixture ratios is monitored in this system. This is
then computed in terms of “injection pulse duration” to automatically compensate for the difference between
the two ratios.
“Fuel trim” refers to the feedback compensation value compared against the basic injection duration. Fuel trim
includes short term fuel trim and long term fuel trim.
“Short term fuel trim” is the short-term fuel compensation used to maintain the mixture ratio at its theoretical
value. The signal from heated oxygen sensor 1 indicates whether the mixture ratio is RICH or LEAN compared
to the theoretical value. The signal then triggers a reduction in fuel volume if the mixture ratio is rich, and an
increase in fuel volume if it is lean.
“Long term fuel trim” is overall fuel compensation carried out long-term to compensate for continual deviation
of the short term fuel trim from the central value. Such deviation will occur due to individual engine differences,
wear over time and changes in the usage environment.
PBIB0121E
EC-570
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ON BOARD DIAGNOSTIC (OBD) SYSTEM
DIAGNOSTIC TEST MODE I — MALFUNCTION WARNING
These DTC numbers are clarified in Diagnostic Test Mode II (SELF-DIAGNOSTIC RESULTS)
DIAGNOSTIC TEST MODE II — SELF-DIAGNOSTIC RESULTS
In this mode, the DTC and 1st trip DTC are indicated by the number of blinks of the MI as shown below.
The DTC and 1st trip DTC are displayed at the same time. If the MI does not illuminate in diagnostic test mode
I (Malfunction warning), all displayed items are 1st trip DTCs. If only one code is displayed when the MI illumi-
nates in diagnostic test mode II (SELF-DIAGNOSTIC RESULTS), it is a DTC; if two or more codes are dis-
played, they may be either DTCs or 1st trip DTCs. DTC No. is same as that of 1st trip DTC. These unidentified
codes can be identified by using the CONSULT-II. A DTC will be used as an example for how to read a code.
A particular trouble code can be identified by the number of four-digit numeral flashes. The “zero” is indicated
by the number of ten flashes. The length of time the 1,000th-digit numeral flashes on and off is 1.2 seconds
consisting of an ON (0.6-second) - OFF (0.6-second) cycle.
The 100th-digit numeral and lower digit numerals consist of a 0.3-second ON and 0.3-second OFF cycle.
A change from one digit numeral to another occurs at an interval of 1.0-second OFF. In other words, the later
numeral appears on the display 1.3 seconds after the former numeral has disappeared.
A change from one trouble code to another occurs at an interval of 1.8-second OFF.
In this way, all the detected malfunctions are classified by their DTC numbers. The DTC 0000 refers to no mal-
function. (See EC-533, "
INDEX FOR DTC" )
How to Erase Diagnostic Test Mode II (Self-diagnostic Results)
The DTC can be erased from the back up memory in the ECM by depressing accelerator pedal. Refer to EC-
569, "HOW TO SWITCH DIAGNOSTIC TEST MODE" .
If the battery is disconnected, the DTC will be lost from the backup memory within 24 hours.
Be careful not to erase the stored memory before starting trouble diagnoses.
DIAGNOSTIC TEST MODE II — HEATED OXYGEN SENSOR 1 MONITOR
In this mode, the MI displays the condition of the fuel mixture (lean or rich) which is monitored by the heated
oxygen sensor 1.
*: Maintains conditions just before switching to open loop.MI Condition
ON When the malfunction is detected.
OFF No malfunction.
PBIA3905E
MI Fuel mixture condition in the exhaust gas Air fuel ratio feedback control condition
ON Lean
Closed loop system
OFF Rich
*Remains ON or OFF Any condition Open loop system
EC-612
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TROUBLE DIAGNOSIS
ACTIVE TEST MODE
Test Item
*:Leaving cooling fan OFF with CONSULT-II while engine is running may cause the engine to overheat.TEST ITEM CONDITION JUDGEMENT CHECK ITEM (REMEDY)
FUEL INJEC-
TION
Engine: Return to the original
trouble condition
Change the amount of fuel injec-
tion using CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.
Harness and connectors
Fuel injector
Heated oxygen sensor 1
IGNITION TIM-
ING
Engine: Return to the original
trouble condition
Timing light: Set
Retard the ignition timing using
CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.
Perform Idle Air Volume Learning.
POWER BAL-
ANCE
Engine: After warming up, idle
the engine.
Air conditioner switch OFF
Shift lever: N (A/T), Neutral (M/T)
Cut off each injector signal one at
a time using CONSULT-II.Engine runs rough or dies.
Harness and connectors
Compression
Fuel injector
Power transistor
Spark plug
Ignition coil
COOLING FAN*
Ignition switch: ON
Turn the cooling fan LOW, HI,
OFF with CONSULT-II.Cooling fan moves and stops.
Harness and connectors
Cooling fan relay
Cooling fan motor
ENG COOLANT
TEMP
Engine: Return to the original
trouble condition
Change the engine coolant tem-
perature using CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.
Harness and connectors
Engine coolant temperature sen-
sor
Fuel injector
FUEL PUMP
RELAY
Ignition switch: ON (Engine
stopped)
Turn the fuel pump relay ON and
OFF using CONSULT-II and lis-
ten to operating sound.Fuel pump relay makes the operat-
ing sound.Harness and connectors
Fuel pump relay
PURG VOL
CONT/V
Engine: After warming up, run
engine at 1,500 rpm.
Change the EVAP canister purge
volume control solenoid valve
opening percent using CON-
SULT-II.Engine speed changes according to
the opening percent.Harness and connectors
Solenoid valve
V/T ASSIGN
ANGLE
Engine: Return to the original
trouble condition
Change intake valve timing using
CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.
Harness and connectors
Intake valve timing control sole-
noid valve
TROUBLE DIAGNOSIS
EC-613
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EC
REAL TIME DIAGNOSIS IN DATA MONITOR MODE (RECORDING VEHICLE DATA)
Description
CONSULT-II has two kinds of triggers and they can be selected by touching “SETTING” in “DATA MONITOR”
mode.
1. “AUTO TRIG” (Automatic trigger):
The malfunction will be identified on the CONSULT-II screen
in real time.
In other words, DTC/1st trip DTC and malfunction item will be
displayed if the malfunction is detected by ECM.
At the moment a malfunction is detected by ECM, “MONI-
TOR” in “DATA MONITOR” screen is changed to “Recording
Data ... xx%” as shown at right, and the data after the mal-
function detection is recorded. Then when the percentage
reached 100%, “REAL-TIME DIAG” screen is displayed. If
“STOP” is touched on the screen during “Recording Data ...
xx%”, “REAL-TIME DIAG” screen is also displayed.
The recording time after the malfunction detection and the
recording speed can be changed by “TRIGGER POINT” and
“Recording Speed”. Refer to CONSULT-II Operation Manual.
2. “MANU TRIG” (Manual trigger):
DTC/1st trip DTC and malfunction item will not be displayed
automatically on CONSULT-II screen even though a malfunc-
tion is detected by ECM.
DATA MONITOR can be performed continuously even though
a malfunction is detected.
Operation
1. “AUTO TRIG”
While trying to detect the DTC/1st trip DTC by performing the DTC Confirmation Procedure, be sure to
select to “DATA MONITOR (AUTO TRIG)” mode. You can confirm the malfunction at the moment it is
detected.
While narrowing down the possible causes, CONSULT-II should be set in “DATA MONITOR (AUTO
TRIG)” mode, especially in case the incident is intermittent.
When you are inspecting the circuit by gently shaking (or twisting) the suspicious connectors, compo-
nents and harness in the “DTC Confirmation Procedure”, the moment a malfunction is found the DTC/
1st trip DTC will be displayed. (Refer to “Incident Simulation Tests” in GI-23, "
How to Perform Efficient
Diagnosis for an Electrical Incident" .)
2. “MANU TRIG”
If the malfunction is displayed as soon as “DATA MONITOR” is selected, reset CONSULT-II to “MANU
TRIG”. By selecting “MANU TRIG” you can monitor and store the data. The data can be utilized for fur-
ther diagnosis, such as a comparison with the value for the normal operating condition.
SEF705Y
SEF707X
TROUBLE DIAGNOSIS
EC-615
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CONSULT-II Reference Value in Data Monitor ModeEBS010XE
Remarks:
Specification data are reference values.
Specification data are output/input values which are detected or supplied by the ECM at the connector.
* Specification data may not be directly related to their components signals/values/operations.
i.e. Adjust ignition timing with a timing light before monitoring IGN TIMING, because the monitor may show the specification data in
spite of the ignition timing not being adjusted to the specification data. This IGN TIMING monitors the data calculated by the ECM
according to the signals input from the camshaft position sensor and other ignition timing related sensors.
MONITOR ITEM CONDITION SPECIFICATION
ENG SPEED
Run engine and compare CONSULT-II value with the tachometer indi-
cation.Almost the same speed as the
tachometer indication.
MAS A/F SE-B1 See EC-620, "
TROUBLE DIAGNOSIS - SPECIFICATION VALUE" .
B/FUEL SCHDL See EC-620, "
TROUBLE DIAGNOSIS - SPECIFICATION VALUE" .
A/F ALPHA-B1 See EC-620, "
TROUBLE DIAGNOSIS - SPECIFICATION VALUE" .
COOLAN TEMP/S
Engine: After warming up More than 70°C (158°F)
HO2S1 (B1)
Engine: After warming upMaintaining engine speed at 2,000
rpm0 - 0.3V ←→ Approx. 0.6 - 1.0V
HO2S2 (B1)
Engine: After warming up
Keeping the engine speed
between 3,500 and 4,000 rpm for
1 minute and at idle for 1 minute
under no loadRevving engine from idle to 3,000
rpm quickly.0 - 0.3V ←→ Approx. 0.6 - 1.0V
HO2S1 MNTR (B1)
Engine: After warming upMaintaining engine speed at 2,000
rpmLEAN ←→ RICH
Changes more than 5 times dur-
ing 10 seconds.
HO2S2 MNTR (B1)
Engine: After warming up
Keeping the engine speed
between 3,500 and 4,000 rpm for
1 minute and at idle for 1 minute
under no loadRevving engine from idle to 3,000
rpm quickly.LEAN ←→ RICH
VEH SPEED SE
Turn drive wheels and compare CONSULT-II value with the speedome-
ter indication.Almost the same speed as the
speedometer indication.
BATTERY VOLT
Ignition switch: ON (Engine stopped) 11 - 14V
ACCEL SEN 1
Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released 0.5 - 1.0V
Accelerator pedal: Fully depressed 4.0 - 4.7V
ACCEL SEN 2*
1Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released 0.3 - 1.2V
Accelerator pedal: Fully depressed 3.9 - 4.8V
THRTL SEN 1
THRTL SEN 2*
1
Ignition switch: ON
(Engine stopped)Accelerator pedal: Fully released More than 0.36V
Shift lever: D (A/T), 1st (M/T) Accelerator pedal: Fully depressed Less than 4.75V
START SIGNAL
Ignition switch: ON → START → ON OFF → ON → OFF
CLSD THL POS
Ignition switch: ONAccelerator pedal: Fully released ON
Accelerator pedal: Slightly
depressedOFF
AIR COND SIG
Engine: After warming up, idle
the engineAir conditioner switch: OFF OFF
Air conditioner switch: ON
(Compressor operates.)ON
P/N POSI SW
Ignition switch: ONShift lever:
P or N (A/T), Neutral (M/T)ON
Shift lever: Except above OFF
PW/ST SIGNAL
Engine: After warming up, idle
the engineSteering wheel is not being turned OFF
Steering wheel is being turned ON
EC-652
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DTC P0117, P0118 ECT SENSOR
DTC P0117, P0118 ECT SENSORPFP:22630
Component DescriptionEBS010Y7
The engine coolant temperature sensor is used to detect the engine
coolant temperature. The sensor modifies a voltage signal from the
ECM. The modified signal returns to the ECM as the engine coolant
temperature input. The sensor uses a thermistor which is sensitive to
the change in temperature. The electrical resistance of the ther-
mistor decreases as temperature increases.
*: This data is reference value and is measured between ECM terminal 72 (Engine
coolant temperature sensor) and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
On Board Diagnosis LogicEBS010Y8
FAIL-SAFE MODE
When this malfunction is detected, the ECM enters fail-safe mode and the MI lights up.
SEF594K
Engine coolant
temperature°C (°F)Voltage* V Resistance kΩ
−10 (14) 4.4 7.0 - 11.4
20 (68) 3.5 2.1 - 2.9
50 (122) 2.2 0.68 - 1.00
90 (194) 0.9 0.236 - 0.260
SEF012P
DTC No. Trouble Diagnosis Name DTC Detecting Condition Possible Cause
P0117
0117Engine coolant temperature
sensor circuit low inputAn excessively low voltage from the sensor
is sent to ECM.
Harness or connectors
(The sensor circuit is open or shorted.)
Engine coolant temperature sensor P0118
0118Engine coolant temperature
sensor circuit high inputAn excessively high voltage from the sensor
is sent to ECM.
Detected items Engine operating condition in fail-safe mode
Engine coolant temper-
ature sensor circuitEngine coolant temperature will be determined by ECM based on the time after turning ignition switch ON
or START. CONSULT-II displays the engine coolant temperature decided by ECM.
ConditionEngine coolant temperature decided
(CONSULT-II display)
Just as ignition switch is turned ON or START 40°C (104°F)
More than approx. 4 minutes after ignition ON or
START80°C (176°F)
Except as shown above40 - 80°C (104 - 176°F)
(Depends on the time)
When the fail-safe system for engine coolant temperature sensor is activated, the cooling fan operates
while engine is running.
EC-666
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DTC P0132 HO2S1
DTC P0132 HO2S1PFP:22690
Component DescriptionEBS010YM
The heated oxygen sensor 1 is placed into the exhaust manifold. It
detects the amount of oxygen in the exhaust gas compared to the
outside air. The heated oxygen sensor 1 has a closed-end tube
made of ceramic zirconia. The zirconia generates voltage from
approximately 1V in richer conditions to 0V in leaner conditions. The
heated oxygen sensor 1 signal is sent to the ECM. The ECM adjusts
the injection pulse duration to achieve the ideal air-fuel ratio. The
ideal air-fuel ratio occurs near the radical change from 1V to 0V.
CONSULT-II Reference Value in Data Monitor ModeEBS010YN
Specification data are reference values.
On Board Diagnosis LogicEBS010YO
To judge the malfunction, the diagnosis checks that the heated oxy-
gen sensor 1 output is not inordinately high.
SEF463R
SEF288D
MONITOR ITEM CONDITION SPECIFICATION
HO2S1 (B1)
Engine: After warming up Maintaining engine speed at 2,000 rpm0 - 0.3V ←→ Approx. 0.6 - 1.0V
HO2S1 MNTR (B1)LEAN ←→ RICH
Changes more than 5 times during
10 seconds.
SEF301UA
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0132
0132Heated oxygen sensor 1
circuit high voltageAn excessively high voltage from the sensor
is sent to ECM.
Harness or connectors
(The sensor circuit is open or shorted.)
Heated oxygen sensor 1
DTC P0132 HO2S1
EC-671
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6. CHECK HEATED OXYGEN SENSOR 1
Refer to EC-671, "
Component Inspection" .
OK or NG
OK >> GO TO 7.
NG >> Replace heated oxygen sensor 1.
7. CHECK INTERMITTENT INCIDENT
Refer to EC-624, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
>>INSPECTION END
Component InspectionEBS010YS
HEATED OXYGEN SENSOR 1
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select “MANU TRIG” and adjust “TRIGGER POINT” to 100% in “DATA MONITOR” mode with CONSULT-
II.
3. Select “HO2S1 (B1)” and “HO2S1 MNTR (B1)”.
4. Hold engine speed at 2,000 rpm under no load during the follow-
ing steps.
5. Touch “RECORD” on CONSULT-II screen.
6. Check the following.
“HO2S1 MNTR (B1)” in “DATA MONITOR” mode changes
from “RICH” to “LEAN” to “RICH” more than 5 times in 10 sec-
onds.
5 times (cycles) are counted as shown at right.
“HO2S1 (B1)” voltage goes above 0.6V at least once.
“HO2S1 (B1)” voltage goes below 0.3V at least once.
“HO2S1 (B1)” voltage never exceeds 1.0V.
CAUTION:
Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7
in) onto a hard surface such as a concrete floor; use a new one.
SEF646Y
SEF217YA
SEF648Y